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Subject[PATCH 12/12] lockdep: enable lock_page lockdep annotation
With everything ready, connect the dots.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/lockdep.h | 7 +++++++
include/linux/pagemap.h | 10 ++++++++++
mm/filemap.c | 35 +++++++++++++++++++++++++++++++++++
3 files changed, 52 insertions(+)
Index: linux-2.6/include/linux/lockdep.h
===================================================================
--- linux-2.6.orig/include/linux/lockdep.h
+++ linux-2.6/include/linux/lockdep.h
@@ -253,6 +253,13 @@ extern void lockdep_init_map(struct lock
struct lock_class_key *key, int subclass);

/*
+ * To initialize a lockdep_map statically use this macro.
+ * Note that _name must not be NULL.
+ */
+#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
+ { .name = (_name), .key = (void *)(_key), }
+
+/*
* Reinitialize a lock key - for cases where there is special locking or
* special initialization of locks so that the validator gets the scope
* of dependencies wrong: they are either too broad (they need a class-split)
Index: linux-2.6/include/linux/pagemap.h
===================================================================
--- linux-2.6.orig/include/linux/pagemap.h
+++ linux-2.6/include/linux/pagemap.h
@@ -157,12 +157,22 @@ extern void FASTCALL(__lock_page(struct
extern void FASTCALL(__lock_page_nosync(struct page *page, unsigned long ip));
extern void FASTCALL(unlock_page_nocheck(struct page *page));

+extern struct lockdep_map *page_lock_map(struct page *page);
+
static inline void __lock_page_check(struct page *page, int try, unsigned long ip)
{
+ /*
+ * use recursive read locks to annotate the page lock.
+ * this allows us to have a single lock instance per filesystem.
+ * obviously this reduces the usefulness of the lock checker
+ * but it also keeps struct page from bloating.
+ */
+ lock_acquire(page_lock_map(page), 0, try, 2, 2, ip);
}

static inline void __unlock_page_check(struct page *page, unsigned long ip)
{
+ lock_release(page_lock_map(page), 1, ip);
}

/*
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -556,6 +556,41 @@ void end_page_writeback(struct page *pag
}
EXPORT_SYMBOL(end_page_writeback);

+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key lock_page_key;
+static struct lockdep_map lock_page_map =
+ STATIC_LOCKDEP_MAP_INIT("lock_page", &lock_page_key);
+
+struct lockdep_map *page_lock_map(struct page *page)
+{
+ struct address_space *mapping;
+ struct inode *inode;
+ struct super_block *sb;
+ struct file_system_type *type;
+ struct lockdep_map *map = &lock_page_map;
+
+ mapping = page_mapping(page);
+ if (!mapping)
+ goto out;
+
+ inode = mapping->host;
+ if (!inode)
+ goto out;
+
+ sb = inode->i_sb;
+ if (!sb)
+ goto out;
+
+ type = sb->s_type;
+ if (type)
+ map = &type->s_mapping_map;
+
+out:
+ return map;
+}
+EXPORT_SYMBOL(page_lock_map);
+#endif
+
/**
* __lock_page - get a lock on the page, assuming we need to sleep to get it
* @page: the page to lock
--

-
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